The Choice to Have Artificial Blood: Less than the Best?

Controversy has erupted around whether experiments to test artificial blood should stop. Experimental blood substitutes raised the risk of heart attack and death, yet U.S. regulators allowed human testing to continue despite warning signs, says a scathing new report.

Blood substitutes, or artificial blood, could be stored for years without refrigeration, and be used in battlefield situations. It would carry no risk risk of infection with hepatitis or HIV. It would be an acceptable alternative to Jehovah’s Witnesses who refuse life saving blood transfusions.
In a new report, researchers pooled data from 16 separate studies of five different blood substitutes, involving over 3,700 patients. Researchers found a 30 percent higher risk of death overall for patients who received transfusions using the blood substitutes. The risk of heart attack was nearly tripled in the groups receiving blood substitutes.

“Experts speculate that hemoglobin in the blood substitutes scavenges nitric oxide from the blood, causing blood vessels to constrict and sticky platelets to build up. That increases the risk of heart attacks.”

These researchers claim that there was enough evidence by 2000 available to the regulatory agency, the U.S. Food and Drug Administration, to conclude that artificial blood was unsafe. However, the FDA defended its decision to continue the trials, and artificial blood manufacturers continue to call for continued trials, on the basis that pooling studies of the use of artificial blood for different conditions (surgery, stroke, trauma) might obscure different effects in different conditions.

Should such studies stop? This is a difficult question to answer and one which requires detailed statistical knowledge. What is more important is that people in such trials should be informed of the knowledge as it stands of the risks of artificial blood compared to natural blood. They need to know the facts as best they are known before they decide whether to take part in any experiment. It is very often the case that there is a significant lag between when relevant information is known to researchers or the academic community, and when it is passed on to participants of clinical trials.

There is a broader point. Artificial blood may never be as safe or as effective as natural blood. But that would not preclude it being offered as an alternative, if it were safe and effective enough. Some, like Jehovah’s Witnesses, would opt for artificial blood rather than nothing. And some might place higher value on avoiding infection. What is key is that anyone offered artificial blood must be fully informed of the best evidence for its risks and benefits, and those of the alternatives.

Increasingly, society will be faced with products which have complex risk/benefit profiles. It is critical that consumers understand these if they are to make autonomous choices. We can use and even test alternatives which are less than the best, provided we give people all the information, and they understand it and voluntarily to choose something which is less than the best.

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